The background art comprises two main groups viz. conventional carding machines hereinafter referred to as the prior art and Robert's specifications U.S. Pat. No. 4,090,276, GB. 1,412,109 and GB 1,075,444 which particularly concern the present invention and are hereinafter referred to as the relevant prior art. These latter specifications may briefly be described as providing a carding machine incorporating a train of at least three adjacent co-operating rollers, each roller of which has a first set of effective teeth which are angled forwardly (with respect to the direction of motion) and a second set of effective teeth which are angled rearwardly and which may also incorporate a roller having threaded-on rings of teeth; further, the teeth co-operate in point to point fashion and further, each of the said adjacent rollers in the train runs at a faster surface speed than its predecessor.
In the parts of this specification and claims relating to the present invention, certain words and expressions have special meanings ascribed to them as follows:
A `carding machine` is a machine used for the opening of staple fibres and in this specification may include machines used for attenuating, aligning and combing fibres and other related operations. PA1 A `roller` is a part of a carding machine in which teeth are incorporated. In this specification, when referring to the relevant prior art, the roller is made up in two parts, the core and its separate card clothing which is usually wound on to the core. In one instance, however, the card clothing is made up of endless rings which are threaded on to the core. Two important distinctions between the prior art, the relevant prior art and one preferred form of the present invention is that in one section of the latter rings of teeth are interleaved and are, for this purpose, secured in precisely predetermined positions on the roller.
In one preferred form of the present invention, a roller consists of a roller bearing means and a special outer part in which the teeth are rooted.
`Special outer part` is the rigid outer part of a roller used in one preferred form of the present invention and is preferably made of steel. It may be integral with the roller bearing means or be a thick metal sleeve which is secured to the roller bearing means.
`Teeth` are projections attached to rollers said teeth acting on the fibres to card, open, attenuate and/or comb them. `Circumferential` describes a feature in a roller which runs around the circumference of a roller substantially at a right angle to the axis.
`Axial` describes a feature in a roller which runs along, the perimeter of a roller substantially in the direction of the axis.
`A ring of teeth` is a circle of teeth at a right angle to the axis of a roller.
`The base of a tooth` in one preferred form of the present invention is that part of a tooth by which it is attached to the special outer part of a roller. Preferably the teeth, the base and the special outer part are integral with each other. Alternatively, `The base of a tooth` might include the flexible wire base of metallic wound-on teeth if the said base were integral with the said teeth and, for instance, swaged into grooves machined in the said special outer part. The criterion for the said preferred for is that the bases must be secured in predetermined positions in relation to the axis of the roller. Nevertheless, in one form of the invention the base of a tooth is the flexible wire base of wound-on teeth.
An `angled forward` tooth has an effective leading edge inclined in the direction of rotation.
An `angled rearward` tooth has an effective trailing edge inclined in the direction opposite to that of rotation.
A `forward-rearward tooth` combines the features of the above teeth and has effective leading and trailing edges.
An `angled forward-backward facing tooth` is a tooth in which the leading edge is inclined in the direction of rotation and the trailing edge is backward facing but is also inclined in the direction of rotation.
The `trailing edge` is the backward facing edge of a tooth when the roller is rotating in its normal direction. It is not necessarily `angled rearwardly` as in the relevant prior art.
The `height` of a tooth is the distance between its outside edge and its base where it ceases to be effective as a tooth.
A `blade` is a circumferential edge connecting the points on the trailing and leading edges of a single tooth.
`Surface teeth` are adapted to card in point to point fashion with teeth in a co-operating roller across a small gap between the outermost parts of said teeth as distinct from interleaved teeth.
`Wound-on teeth` are surface teeth attached spirally by wrapping around a conventional carding machine roller as distinct from being made spirally, for instance by machining, in the special outer part of a roller.
Rings of teeth in the same family' are related to each other by, for instance, there being a regular mathematical connection with rings of teeth on a co-operating roller even though the rings are not necessarily the same distance apart on both rollers. Related teeth may also share a distinctive shape; such rings are not necessarily the same height above their base as those on the co-operating roller.
`Swaged` means fixed in position, for instance in a groove, by an operation such as rolling or hammering.
`Rooted` means that the base of a tooth is either integral with the special outer part of a roller or is secured in a predetermined position, for instance by swaging in a groove, in the special outer part of a roller.
`Co-operating rollers` are adjacent rollers the teeth of which are working on fibres passing between the said rollers.
`Zone of co-operation` means the area between two co-operating rollers where at least some carding takes place.
In this specification the phrase `interleaved rings of teeth` means that such rings have the following characteristics:
1. Each ring of teeth is secured in the direction of the axis of its roller in a precisely predetermined position relative to a datum point so that rings of teeth on one co-operating roller may rotate and continue to rotate between rings of teeth similarly constructed on an adjacent co-operating roller without interference between the teeth on any co-operating rollers. 2. There is a predetermined distance between the walls of all interleaved teeth so that there is maintained a substantial clearance between the walls of said teeth so that a) there is no scissor action between teeth which could cause fibre breakage and b) sufficient room is left between teeth to allow carding to proceed smoothly.
A `lifting surface` is a part of a tooth which is adapted to urge the fibres towards the outside edges of the teeth, to reduce the tendency of fibres to be drawn between the rings of teeth thus reducing fettling and to allow more tolerance in adjustment so that teeth in a succeeding roller can engage the fibres.
A `tuft` is a small easily carded bunch of fibres,
A `wad` is a larger bunch of fibres which needs to be broken up before being carded.
Interstices' are small spaces in the component parts of a roller in which fibres are trapped accidentally.
The `take-off` is the final removal of the fibres from the doffer.